Circuit interrupter



March 27, 1945. M LEEDS ET 2,372,589

CIRCUIT INTERRUPTER Filed Sept. 18, 1942 2 Sheets-Sheet l Mayne/fa March 27, 1945. w. M. LEEDS ET AL CIRCUIT INTERRUPTER Filed Sept. 1 8, 1942 2 Sheets-Sheet 2 INVENTORS M A eea s wumsssEs:

Mb fhro 00(509/0/0/0 EBamsr: BY

a/ ATTORN Pressure generating Patented Mar.-2 7, 1945 UNITED STATES PATENT OFFICE Y a 2,372,589 I Winthrop Mi Leeds,

1?. Baker,

Wilkinsburg, Turtle Creek. Pa... m nors to W s and Benjamin inghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 18, 1842, No. 458,778

of arc extinguishing fluid.

An object 01' the present invention is to provide an improved arc extinguishing structure in which a pressure generating arc and an interrupting to eflectively quench the latter. Another object is to provide an improved ciruit interrupter'in which a pressure generatingarc and an interrupting arc are established, the interrupting arc being established adJacent to a constricted arcing slot and to provide improved Passage means for erating arc with the interrupting arc to force the latter by fluid flow into said constricted arcing slot to efl'ect the exti ction ot'said interrupting arc therein.

Another object is to provide an improved circuit interrupting structure in which a pressure generating arc is formed together with an interrupting arc, and to dispose in said interrupting structure a piston to prevent a contamination of the fluid flow toward said interrupting arc.

Another object is to-provide an improved circuit interrupter in which a piston is secured to and movable with the intermediate contact so that the contaminated arc extinguishing fluid immediately adjacent to the pressure generating arc is not forced into the region surrounding the interrupting arc to lower oi'the fluid adjacent to the interrupting are.

secured to and movable with'the intermediate contact to not only prevent a contamination of the fluid adjacent the interrupting are from the pressure generating are, but also to provide sumcient fluid flow during the interruption of small Another object is to provide an improved circonnecting the pressure genthe dielectric strength 11 Claims. (Cl. zoo-15o) cuit interrupter'in which a pressure generating arc and an interrupting arc are established, said interrupting are being drawn adjacent to a constricted arcing slot, with suitable vents disposed along one side of said constricted arcing slot, and to provide magnetic means to cooperate with the fluid flow created by said pressure generating arc to force said interrupting arc laterally toward the constricted arcing slot in the direction oi 10' said vents.

Another object is to provide an improved interrupting structure in which a concentrated blast of fluid is employed both for rapid arc lengthening and for scavenging purposes.

Another more speciflc object is to provide an improved circuit interrupter in which an arc is established, and in which a fluid blast is concentrated and directed against the initially formed portion oi. said are which tends to lengthen the same at a greater rate than the rate of separation of the I to'provide means to prevent such lengthening until relatively low instantaneous values of arcing current. ,7 It will be readily apparent that such a concentrated fluid blast will build up the dielectric strength in the relatively short gap between the contacts to prevent restriking in this region after the greatly lengthened arc itself has been extinguished.

A specific object of the invention is to provide an improved interrupting structure in which both a pressure generating arc and an interrupting arc are established with apiston attached to and movable with the intermediate contact structure, and to provide an improved valve construction associated with the intermediate contact structure.

Another object is to provide an improved circuit interrupter in which both a pressure generating arc and an interrupting are are established, and in which the main movable contact serves as a directing valve to concentrate and direct a blast of fluid from said pressure generating are into the initially formed portion of the interrupting arc to tend to lengthen the same at a greater rate than the'rate of separation of the main contacts.

The term "fluid" as used in the specification and in the appended claims includes gases, liquids, vapors and sprays.

It will be readily apparent to one skilled i th art that our invention is applicable to circuit inmt rs operatin n aseous mediums, such as W l as n liquid mediums. However, for purposes of illustration, and not by way of movable contacts, and

ward to cause oil flowthrough the conduit i! into the lower interruption chamber l4. During the interruption of low R; M. B. currents the pressure generating are It will have little effect on the downward'motion of the piston 1, the

compression spring] being relied upon to produce this downward motion of the p ston 1 and .the consequent oil flow through the conduit II.

It will .be observed that in the interrupter shown in Fig. 1 the magnetic inserts 2i bias the interrupting are 28 toward the vents 36 provided inthe vent plates 32.

This biasing action exerted by the magnetic plates is in the same direction as the oil flow through the conduit 13 and tends to carry the lower terminal of the interrupting are 28 down along the side of the movable contact 6 as shown in Fig. 1. During relatively high instantaneous values of arcing current the cross section of the interrupting arc 2| is too large to permit it to be forced into the restricted arcing slot 26 provided in the plates II, 21 and it. However. when the instantaneous value of arcing current through the interrupting are 28 drops to a relatively small value. that is approaches a. current zeroon the alternating current wave, the cross section of the interrupting are 28 at this time will be suf-= ilciently'small to permit both the oil flow through the conduit II and also the biasing iorce exerted by the magnetic inserts to carry it into the restricted arcing slot 26 and toward the vents II in the vent plates 32. During the time that the are 2. is in the restricted arcng slot 26 the interrupting are 28 rapidly eiongates by the combined action of the magnetic force and the fluid flow to run down the side of the movable contact I to cmsequently attain a considerable length as shown in Fig. l.' It will be observed that the length of the interrupting arc 2B is c nsderably greater than the distance between'the movable contact- 6 and the lower portion oithe intermediate contact I. Thusa distinct advantage in having the magnetic inserts 21 bias the interrupting are 28 in the same direction as the fluid ilow through the conduit is is that the are 28 is lengthened exceedngly rapidly as c mpared the conduit II in the short gap between the movable contact t and the intermed ate contact to build up the dielectric between the movable con-- tact I and the intermediate contact 5 to prevent restriking in this gap after the are 28 has been extinguished in the narrow end of the slot. This scavenging action is essential to obtain max'mum benefits of the arc lengthening action.

'When the cross section of the interr pting are Ills suihcientiy small for it to enter'the nararc extinguishing chamber M to eifect an isolating break in the open circuit podtion o! the ine terrupter. The check valve Ii will open upon a subsidence of pressure within the pressuregem crating chamber II to allow escape of sand to permit a fresh quantity of .arc extinguishing oil to enter the pressure. generating chamber ll.

Fresh oil will also enter the interrupting chamber ll through the vents It and through the beveled slot "in the bottom insulating plstejl.

In the closing-of the interrupter it will be apparent that the movable contact I will strike the intermediate contact I, movlng'it slightly. upward against the biasing action of the compression spring I to open the annular opening I provided in the piston I, to permit oil to out of the pressure generating cham er I! during the closing of the interrupter. During the opening operation the movable contact 8 oon withdraws from-the intermediate contact I to permit the intermediate contact I to close opening 9 by means of the-pressure within the pressure generating-chamber II and also of the compression spring 4|.- a

:It will be observed that by the provision of a piston 1 decomposed products ofdecomposition from the'pressure generating arc II which tend to lower the dielectricstrength of the oil flowing through the conduit 13 will be prevented from entering the region adjacent the interrupting arc II. Consequently, only 'clean fresh oil of high dielectric strength will be forced by the piston I through the conduit II and into the interrupting chamber l4.

"As stated previously during the interruption of I low R. M. S. currents when the pressure built up '40 in the pressure generating chamber II is relatively small the compression spring I will at this time move the piston I downward to create the row arcingslot 20 it rapidly elongates in a m n- Lner shown in Fig. 1. as previously described, and

is blasted by a transverse ilcw of oil and gas particles flowingtoward the vents 88 in the vent plates-l2. Extinction of the interrupting are 28 soon'iollowsfand the valve actionof the men-- able contact 8 concentrates oil flow from the con- Jduit it into the region between the movable conl mt I and the intermediate contact 5 to build fluid flow through the conduit-I8 necessary for rapid extinction of the interrupting are 28.

Some of the features of the general method of I are extinctionjust described in connection with the interrupter shown in Fi l are set forth and broadly claimed in Patent 2,138,882 which issued November 29, 1938, to Winthrop M. Leeds and Enn'io Ortensi and which was assigned to the Westinghouse Electric & manufacturing Company. a

It will be apparent to one skilled in the art that our invention is readily applicable not only to liquid immersed circuit interrupters but also to circuit interrupter-s operatingin a gaseous medium, such as air. The insulating plates described in connection with the are extinguishing structure I showninFlg.imaybems-dcofasuitable gas evolving material to facilitate the int": ruption of the interrupting arc. the arc extinguishing structure I could be ov rated in air with the insulating plates composed of a suitable gas evolving material such as horn fiber or borlc acid; Merely for purposes of iilustration, and not by way of limitation. we have describedour invention as embodied in an oil immersed circuit interrupter.

Although we have shown and described a specific structure, it is to be understood that the same was only for purposes of ilhis'tration and that changes and modificationsmay be made therein by those skilled" in the art without-departing from the spirit and scope of the appended claims.-

We claim as our invention: 1. In a circuit interrupter, means for establishing a pressure generating arc and an interrupting are, means defining a constricted arcing slot disposed adjacent said interrupting arc, magnetic means for biasing said interrupting arc into said constricted arcing slot, and means utilizing said pressure generating arc to assist said magnetic means in forcing said interrupting are into said constricted arcing slot to eflect its extinction therein.

2. In a circuit interrupter, an arcing chamber, a' stationary contact at one end of said arcing climber, a movable intermediate contact, a piston secured to and movable with said intermediate contact, a movable contact operative i through the other end of said arcing chamber, we stationary contact and said intermediate cooperating to establish a pressure are, said intermediate contact cooperating with said movable contact to form an'interrupting arc, the region about said presgenerating arc being confined by said piston so new prevent contaminated fluid adjacent said pressure generating are from contacting sai interrupting arc.

3. In a circuit interrupter, contact means for establishing a pressure generating arc and an interrupting arc, fluid passage means connecting said arcs, and piston means intermediate said arcs and associated with the contact means for preventing contamination of the fluid adjacent said interrupting arc with the fluid adjacent said pressure generating arc.

4. Inc circuit interrupter, contact means tor establishing a pressure generating arc and for establishing an interrupting are after said pressure generating arc is established, and piston means operative in response to motion 01' the contact means for insuring uncontaminated fluid iiow from said pressure generating arc to said interrupting arcat the time when the latter is established.

5. In a circuit interrupter, a pressure generating chamber, contact means for establishing a pressure generating are within the pressure generating chamber, an interrupting chamber, means for establishing an interrupting are within the interrupting chamber, a single passage connecting said two chambers, piston means disposed in said single passage and responsive tomotinn oi the contact means, and biasing means to operate said piston means during the interruptionoi low currents.

8. In a circuit interrupter, stationary contact means, movable intermediate contact means, and movable contact means, a pressure generating are being established between said stationary contact;

means, said spring being or help in interrupting low currents.

7. In a circuit breaker oi the liquid break type. a pressure generating chamber in which a stationary contact is disposed, a piston disposed within said pressure generating chamber, an intermediate contact secured to and movable withoaid piston, spring means biasing said piston and said intermediate contact away from said stationary contact, an interrupting slot in which a movable contact operates to draw an interrupting arc with said. intermediate contact, venting means disposed along one side of said interrupting slot, passage means connecting said pressure generat ing chamber with said interrupting slot. and valve means disposed in said intermediate contact to facilitate the closing oi said interrupter.

8. In a circuit interrupter, a stationary contact, an intermediate contact, a movable main contact. a pressure generating arc being established between said stationary contact and said intermediate contact, an interrupting are being estab lished between said intermediate contact and said movable main contact, means defining a con- 9. In a circuit interrupter, means for establishing a pressure generating arc and an interrupting are, means defining a constricted arcing slot disposed adjacent said interrupting arc and of such a narrow width that said interrupting arc can only enter said constricted arcing slot during relatively low instantaneous values of arcing current, fluid flow created by said'pressure generating arc biasing said interrupting are into said,

constricted arcing slot, and magnetic means also biasing said interrupting are into said constricted arcing slot.

10. In a circuit interrupter, means for estabiishing a pressure generating arc, means for establishing an interrupting arc, ,slot means disposed adjacent said interrupting are into which 40 said interrupting arc can enter only during relativelylow instantaneous values of arcing current, passage means connecting said arcs to transmit a blast of arc extinguishing fluidirom said pressure generating arc-te said interrupting arc to biasthe latter into said slot means to eiiect its extinction therein, and one or more U-shaped plates oi ma netic material at least partially surrounding said slot means to bias said interrupting are into said slot means.

11. In a circuit interrupter, means for establishlng a pressure generating arc,,means for establishing an interrupting arc, an elongated arcins slot disposed adjacent said interrupting arc, venting means disposed along one side of said elongated arcing slo passage means connectin said two arcs for permitting a. blast of fluid from said pressure generating arc to bias said interrupting arc into said elongated arcing slot toward said venting means, and magnetic means also biasing said interrupting arcinto said elongated arcing slot toward the'venting means.

12. In a circuit interrupter, a stationary contact, an intermediate contact, and a movable main contact. said stationarycontact and saidinter- .mediate contact cooperating to establish a pressure generating arc, said intermediate contact and said movable main contact cooperating to establish an interrupting arc, a relatively narrow arcing slot disposed adjacent to said interrupting are into which said interrupting arc may be forced to cause its extinction, e means connecting said two arcs for permitting a ilow of arc extinguishing fluid to bias said interrupting are into said relatively narrow arcing slot, and a movable piston secured to and movable with said interas'zasso mediate contact to insure uncontaminated fluid flow through said passage means toward said interrupting arc.

13. In a circuit interrupter, mean for establishing a pressure generating arc and an interrupting arc, an elongated arcing slot disposed adjacent said interrupting are and of such narrow width that said interrupting arc can only enter said arcing slot during relatively low instantaneous values of arcing current, passage means connecting said two arcs for permitting a fluid blast from said pressure generating arc to bias said interrupting are into said arcing slot, and piston means for insuring uncontaminated fluid flow through said passage means.

14. In a circuit interrupter, relatively movable contacts for establishing an arc, an elongated arcing slot disposed adjacent said are into which said are may be forced to cause its extinction,

passage means disposed adjacent said relatively movable contacts for transmitting fluid flow toward said are, one of said relatively movable contacts serving at least partially as a valve in said into said values of arcing current, means ior causing fluid flow for biasing said arc into said arcing slot, said movable contact serving a a directing valve tor directing a concentrated .blast oi fluid toward the initially formed portion oi said are.

16. In a circuit interrupter, means for establishing an are, said means comprising a movable contact, a constricted arcing slot of such narrow width that said are may only enter said arcing slot during relatively low instantaneous values of arcing current, passage means for directing a blast of fluid toward said are to bias said are into said arcing slot, magnetic means for biasing said are toward said arcing slot, said movable contact serving at least partially as a fluid directing valve in said passage means.

- 17. In a circuit interrupter, a stationary conarcing slot disposed adjacent said interrupting arc and of such narrow width that said interrupting arc can only enter said arcing slot during relatively low instantaneous values of arcing current, passage means connecting said two area to transmit a flow oi fluid to bias said interrupting arc toward said arcing slot, said movable contact serving at least partially as a'directingvalve so in said passage means.

WINI'HROP M. LEEDS. BENJAMDQ P. BAKER. 

